Archaeologists have delved into the rubbish heaps and cesspits of ancient Greenland
Ancient rubbish can tell us just as much about people as jewellery, weapons or houses. In Greenland, scientists have studied the frozen rubbish heaps of ancient settlements — places where, for centuries, animal bones, food scraps, shells, excrement and household waste were deposited.
Such mounds are called middens. Essentially, they are archaeological ‘rubbish dumps’ and layers of domestic waste that preserve traces of everyday life. In a new study, microbiologists and archaeologists have shown that even after hundreds and thousands of years, microbial traces of humans, animals, farming and hunting can still be found in these layers.
Details
The researchers took samples from ancient rubbish heaps in West and South Greenland. These spanned various periods: Palaeo-Inuit settlements, medieval Norwegian settlements and early colonial layers. In total, the scientists compared 78 samples from rubbish heaps with 143 samples of ordinary soil taken from near the ancient settlements.
They then analysed the microbial DNA in these samples. It turned out that the ancient rubbish differed significantly from ordinary soil. It preserved a distinctive microbial ‘signature’ of human and animal life.
Put simply, the bacteria helped to reveal what had taken place at these sites. In some places, there were traces of decomposing animal tissue. In others, there were remains associated with seals. In other places, there were microbes typical of the human and animal gut. At the Norwegian settlements, the scientists also took samples from areas where livestock might have been kept in winter and where they grazed in summer.
In different layers, they found between 9 and 202 bacterial species per sample, totalling 1,207 species. However, many of the microbes could only be identified approximately: Arctic soils and archaeological deposits remain less well characterised than typical modern environments.
The early colonial layers in the Nuuk area proved particularly interesting. There were remains of decomposing seal skins, and alongside these, the scientists found many bacteria associated with the decomposition of organic matter. In the Norwegian layers, where there were more bones, the microbial composition was different. This suggests that bacteria can provide clues as to exactly what kind of rubbish people left behind.
Were any dangerous diseases found there?
Scientists did indeed detect bacterial DNA, including that of potentially dangerous species such as Clostridium perfringens and Paeniclostridium sordellii. Such bacteria can be linked to food poisoning and severe infections.
However, there is an important caveat: these are primarily traces of DNA, rather than proof that living ancient microbes capable of infecting humans have been preserved in the permafrost. The authors explicitly emphasise that the results should be understood as preserved microbial signatures in archaeological layers, rather than as evidence of viable ancient bacteria.
The researchers did not identify any high-risk pathogenic strains. Moreover, where rubbish heaps had been eroded, the bacteria from them spread only to a limited extent and were quickly replaced by common modern environmental microbes.
Why this is important
This study shows that ancient rubbish is not simply dirt, but an archive of everyday life. It reveals what people ate, which animals they used, where they kept their livestock, what they discarded, and which microbes were part of their daily lives.
This is particularly valuable for Greenland. Various groups of people lived there: Palaeo-Inuit cultures, followed by Norwegian settlers, and then the inhabitants of the early colonial period. They all left traces, but not always in the form of well-preserved artefacts. Microbial DNA helps us to see the invisible part of history.
There is also a contemporary reason for interest. The Arctic is warming faster than the global average, and the permafrost, which has long preserved organic matter, is gradually thawing and eroding. Scientists therefore believe that such archaeological sites are worth monitoring: not because of any immediate threat, but to understand which microbes and genes might emerge from the ancient deposits.
Background
In conventional archaeology, rubbish heaps have long been regarded as a valuable source of information. Bones, shells, tools, fragments of objects and food remains are found in them. But microbiology adds a new layer of information.
For example, if there are many gut-associated bacteria in the rubbish, this may indicate the presence of human or animal faeces. If decomposing bacteria predominate, this may suggest the presence of hides, carcasses or other organic remains. If traces of livestock are found near a settlement, it is possible to gain a better understanding of how the farm was organised.
The researchers also found antibiotic-resistance genes. This is not necessarily a sign of modern medicine: many such genes have existed in nature for a long time, as microbes have been competing with one another for millions of years. However, the discovery shows that such genes can persist in soil and archaeological layers for a very long time.
Source
Study: Lorrie Maccario et al., “Microbial composition of archaeological middens: tracing human footprints through centuries in Greenland’s ancient settlements”, Frontiers in Microbiology, 2026.